Summary of Impact of Derivative Financial Instruments to Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net Investment Hedges \| Foreign Currency Contracts
Derivative [Line Items]
Realized Gains (Losses)		$ (13)	$ (8)	$ (35)
Freestanding Derivatives
Derivative [Line Items]
Realized Gains (Losses)	$ 12,836	(9,402)	9,974	(8,917)
Net Change in Unrealized Gain (Loss)	39,327	15,430	(1,771)	15,200
Freestanding Derivatives \| Total Return Swaps
Derivative [Line Items]
Realized Gains (Losses)	173		174
Net Change in Unrealized Gain (Loss)	(5)		52
Freestanding Derivatives \| Credit Default Swap
Derivative [Line Items]
Realized Gains (Losses)	(107)	268	(508)	(1,658)
Net Change in Unrealized Gain (Loss)	615	1,214	488	3,161
Freestanding Derivatives \| Foreign Currency Contracts
Derivative [Line Items]
Realized Gains (Losses)	12,321	(6,663)	8,238	(3,312)
Net Change in Unrealized Gain (Loss)	1,456	14,642	(2,272)	12,682
Freestanding Derivatives \| Interest Rate Contracts
Derivative [Line Items]
Realized Gains (Losses)	449	(3,007)	2,070	(3,947)
Net Change in Unrealized Gain (Loss)	$ 37,261	$ (426)	$ (39)	$ (643)

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- Definition

The difference between the book value and the sale price of options, swaps, futures, forward contracts, and other derivative instruments. This element refers to the gain (loss) included in earnings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(h))
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

+ References

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